Beorn is a character created by J. R. R. Tolkien, and part of his Middle-earth legendarium. He appears in The Hobbit as a "skin-changer", a man who could assume the form of a great black bear. His descendants or kinsmen, a group of Men known as the Beornings, dwell in the upper Vales of Anduin, between Mirkwood and the Misty Mountains, and are counted among the Free Peoples of Middle-earth who oppose Sauron's forces during the War of the Ring. Like the powerful medieval heroes Beowulf and Bödvar Bjarki, whose names both mean "bear", he exemplifies the Northern courage that Tolkien made a central virtue in The Lord of the Rings.

Middle-earth is the setting of much of the English writer J. R. R. Tolkien's fantasy. The term is equivalent to the Miðgarðr of Norse mythology and Middangeard in Old English works, including Beowulf. Middle-earth is the human-inhabited world, that is, the central continent of the Earth, in Tolkien's imagined mythological past. Tolkien's most widely read works, The Hobbit and The Lord of the Rings, are set entirely in Middle-earth. "Middle-earth" has also become a short-hand term for Tolkien's legendarium, his large body of fantasy writings, and for the entirety of his fictional world.